The present invention relates to a fine crystalline thin wire of cobalt base alloy having improved resistance to wear, bending and corrosion, as well as to a process for producing such a wire.
Thin metal wires in extensive use as industrial materials include stainless steel wires, piano wires, Elgiloy alloy wires, powder-high speed steel wires and hard metal wires. However, stainless steel wires, piano wires and Elgiloy alloy wires are low in wear resistance, powder-high speed steel wires do not have high corrosion resistance, and hard metal wires are poor in resistance to bending and corrosion. These prior art thin wires are typically manufactured by powder metallurgical techniques and wire drawing methods but these methods of production require complicated steps which have to be carried out with expensive equipment and the cost of the final products is inevitably high.
Boron-containing transition metal alloys having improved strength, hardness and corrosion resistance and a process for producing filaments of these alloys have been proposed (U.S. Pat. No. 4,365.994). The proposed method consists basically of making an amorphous filament by the melt spinning of an alloy with a specified composition and subsequently heat-treating the filament to produce a high-strength filament in which uniformly dispersed ultrafine grains of a crystal phase have developed. In order to avoid brittleness due to the pressence of excessive silicon, the proposed process incorporates either no silicon at all or only a small amount, so that the filament produced is low in wear resistance and the alloy does not have good spinnability. In addition, the alloy which contains iron is low in corrosion resistance and does not ensure completely satisfactory wear resistance. Furthermore, the alloy contains nickel and does not have adequate spinnability. A further problems is that a molten metal must be first spun into amorphous alloy before a heat treatment is conducted and high-strength filaments can be attained only when these steps, which make the production process complicated, are taken.
As will be understood from the above, none of the existing thin metal wires satisfy the requirements for high resistance to wear, bending and corrosion, nor has a process been known by which thin metal wires having these characteristics can be produced in an efficient and economical manner.
As a result of continued efforts to deal with such situations, the present inventors discovered inexpensive and novel alloy compositions having improved spinnability and a high tendency to produce fine crystal grains. Based on this finding, the present inventors have succeeded in developing thin metal wires having improved resistance to wear, bending and corrosion, as well as an economical process for producing such thin wires.